SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '789bcbbba611366bfe09b3ab3116f05880f2158cbcafa523466ad1aee94cdebb' 
  AND token = 'mQS2pWiPUkWuygFxPj3Ewh3AC2o0vFj34187VqD2smk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}